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Corn Genome Map Could Lead to Higher Yields

WASHINGTON, DC, February 28, 2008 (ENS) – The world’s first map of the corn genome was unveiled today by a team of scientists led by Washington University in St. Louis. The researchers have completed a working draft of the corn genome, which they say should accelerate efforts to develop better crop varieties to meet growing demands for food, livestock feed and fuel.

“This first draft of the genome sequence is exciting because it’s the first comprehensive glimpse at the blueprint for the corn plant,” Wilson said.

“Scientists now will be able to accurately and efficiently probe the corn genome to find ways to improve breeding and subsequently increase crop yields and resistance to drought and disease.”

Corn is only the second crop after rice to have its genome sequenced, and scientists will now be able to look for genetic similarities and differences between the crops.

The genetic code of corn consists of two billion bases of DNA, the chemical units that are represented by the letters T, C, G and A, making it similar in size to the human genome, which is 2.9 billion letters long. By comparison, the rice genome is far smaller, containing about 430 million bases.

The challenge for Wilson and his colleagues was to string together the order of the letters, an immense and daunting task both because of the corn genome’s size and its complex genetic arrangements. Corn has 50,000 to 60,000 genes, roughly double the number of human genes.

“Sequencing the corn genome was like putting together a 1,000 piece jigsaw puzzle with lots of blue sky and blue water, with only a few small sailboats on the horizon,” Wilson explains. “There were not a lot of landmarks to help us fit the pieces of the genome together.”

The $29.5 million project was initiated in 2005 and is funded by the National Science Foundation, the U.S. Department of Agriculture and the U.S. Department of Energy.

“Corn is one of the most economically important crops for our nation,” says National Science Foundation Director Arden L. Bement Jr. “Completing this draft sequence of the corn genome constitutes a significant scientific advance and will foster growth of the agricultural community and the economy as a whole.”

Corn is one of the world’s staple foods. (Photo by Scott Bauer courtesy USDA)

Corn is used to make products from breakfast cereal, meat and milk to toothpaste, shoe polish and ethanol.

The team working on the endeavor has already made the sequencing information accessible to scientists worldwide by depositing it in GenBank, an online public DNA database. The genetic data is also available at maizesequence.org.

The draft covers about 95 percent of the corn genome, and scientists will spend the remaining year of the grant refining and finalizing the sequence. “Although it’s still missing a few bits, the draft genome sequence is empowering,” Wilson explains. “Virtually all the information is there, and while we may make some small modifications to the genetic sequence, we don’t expect major changes.”

Scientists at the University of Arizona in Tucson, Cold Spring Harbor Laboratory in New York and Iowa State University worked on the sequencing.

The group sequenced a variety of corn known as B73, developed at Iowa State decades ago. It is noted for its high grain yields and has been used extensively in both commercial corn breeding and in research laboratories.

The National Corn Growers Association applauded the scientific accomplishment and looks forward to its practical applications.

“The completion of a maize draft sequence is the first step in determining the function of all the genes in corn, which in turn, will allow corn growers to plant corn hybrids that are better able to withstand drought and other stresses and are better suited to market and environmental needs,” said Ron Litterer, president of the association. “Consumers will benefit from a more nutritious, abundant and sustainable food supply.”

The United States is the world’s top corn grower, producing 44 percent of the global crop.

In 2007, U.S. farmers produced a record 13.1 billion bushels of corn, an increase of nearly 25 percent over the previous year, according to the U.S. Department of Agriculture.

The 2007 production value of corn was estimated at more than $3 billion. Favorable prices, a growing demand for ethanol and strong export sales have fueled an increase in farmland acreage devoted to corn production.